|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
Journal of Experimental Biology, Vol 202, Issue 22 3225-3237, Copyright © 1999 by Company of Biologists
JOURNAL ARTICLES |
M Girgenrath and RL Marsh
Department of Biology, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA. rmarsh@lynx.dac.neu.edu.
Sound-producing muscles provide the opportunity of studying the limits of power production at high contractile frequencies. We used the work loop technique to determine the power available from the external oblique muscles in two related species of North American gray tree frog, Hyla chrysoscelis and Hyla versicolor. These trunk muscles contract cyclically, powering high-intensity sound production in anuran amphibians. The external oblique muscles in H. chrysoscelis have an in vivo operating frequency of 40-55 Hz at 20-25 degrees C, whereas in H. versicolor these muscles contract with a frequency of 20-25 Hz at these temperatures. In vivo investigations have shown that these muscles use an asymmetrical sawtooth length trajectory (with a longer shortening phase compared with the lengthening phase) during natural cycles. To study the influence of this particular length trajectory on power output, we subjected the muscles to both sinusoidal and sawtooth length trajectories. In both species, the sawtooth trajectory yielded a significantly higher power output than the sinusoidal length pattern. The maximum power output during sawtooth cycles was similar in both species (54 W kg(-)(1) in H. chrysoscelis and 58 W kg(-)(1) in H. versicolor). These values are impressive, particularly at the operating frequencies and temperatures of the muscle. The sinusoidal length trajectory yielded only 60 % of the total power output compared with the sawtooth trajectory (34 W kg(-)(1) for H. chrysoscelis and 36 W kg(-)(1) for H. versicolor). The optimum cycle frequencies maximizing the power output using a sawtooth length pattern were approximately 44 Hz for H. chrysoscelis and 21 Hz for H. versicolor. These frequencies are close to those used by the two species during calling. Operating at higher frequencies, H. chrysoscelis maximized power at a strain amplitude of only 8 % compared with a value of 12 % in H. versicolor. These strains match those used in vivo during calling. The stimulus timing observed in vivo during calling was also similar to that yielding maximum power at optimal frequency in both species (6 ms and 8 ms before the start of shortening in H. chrysoscelis and H. versicolor, respectively). As expected, twitch duration in H. chrysoscelis is much shorter than that in H. versicolor (23 ms and 37 ms, respectively). There was a less remarkable difference between their maximum shortening velocities (V(max)) of 13.6 L(0 )s(-)(1) in H. chrysoscelis and 11.1 L(0 )s(-)(1) in H. versicolor, where L(0) is muscle length. The force-velocity curves are very flat, which increases power output. At the myofibrillar level, the flat force-velocity curves more than compensate for the lower peak isometric force found in these muscles. The data presented here emphasize the importance of incorporating in vivo variables in designing in vitro studies.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati 
Twitter What's this?
This article has been cited by other articles:
|
|
 |
|
  C. J. Leary Hormones and acoustic communication in anuran amphibians Integr. Comp. Biol., October 1, 2009; 49(4): 452 - 470. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. J. Ellerby and G. N. Askew Modulation of flight muscle power output in budgerigars Melopsittacus undulatus and zebra finches Taeniopygia guttata: in vitro muscle performance J. Exp. Biol., November 1, 2007; 210(21): 3780 - 3788. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. J. Ellerby and G. N. Askew Modulation of pectoralis muscle function in budgerigars Melopsitaccus undulatus and zebra finches Taeniopygia guttata in response to changing flight speed J. Exp. Biol., November 1, 2007; 210(21): 3789 - 3797. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. A. Jones, K. S. Lucey, and D. J. Ellerby Efficiency of labriform swimming in the bluegill sunfish (Lepomis macrochirus) J. Exp. Biol., October 1, 2007; 210(19): 3422 - 3429. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. P. H. Elemans, I. L. Y. Spierts, M. Hendriks, H. Schipper, U. K. Muller, and J. L. van Leeuwen Syringeal muscles fit the trill in ring doves (Streptopelia risoria L.) J. Exp. Biol., March 1, 2006; 209(5): 965 - 977. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. S. Tu and T. L. Daniel Submaximal power output from the dorsolongitudinal flight muscles of the hawkmoth Manduca sexta J. Exp. Biol., December 15, 2004; 207(26): 4651 - 4662. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Girgenrath and R. L. Marsh Season and testosterone affect contractile properties of fast calling muscles in the gray tree frog Hyla chrysoscelis Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2003; 284(6): R1513 - R1520. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. N. Askew and R. L. Marsh Muscle designed for maximum short-term power output: quail flight muscle J. Exp. Biol., August 1, 2002; 205(15): 2153 - 2160. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. E. Conley and S. L. Lindstedt Energy-saving mechanisms in muscle: the minimization strategy J. Exp. Biol., August 1, 2002; 205(15): 2175 - 2181. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. N. Askew and R. L. Marsh The mechanical power output of the pectoralis muscle of blue-breasted quail (Coturnix chinensis): the in vivo length cycle and its implications for muscle performance J. Exp. Biol., January 11, 2001; 204(21): 3587 - 3600. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. N. Askew, R. L. Marsh, and C. P. Ellington The mechanical power output of the flight muscles of blue-breasted quail (Coturnix chinensis) during take-off J. Exp. Biol., January 11, 2001; 204(21): 3601 - 3619. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Josephson, J. Malamud, and D. Stokes Power output by an asynchronous flight muscle from a beetle J. Exp. Biol., January 9, 2000; 203(17): 2667 - 2689. [Abstract] [PDF]
|
|
|
|
|
|
R. Marsh Contractile properties of muscles used in sound production and locomotion in two species of gray tree frog J. Exp. Biol., January 11, 1999; 202(22): 3215 - 3223. [Abstract] [PDF]
|
|
